This research will address how tactile information contributes to proprioception and control of reaching in healthy subjects and in individuals with Parkinson's Disease. Several studies have shown repetitive reaching movements are more accurate when endpoint contact of the fingertip occurs. This study will determine if tactile cues improves subsequent reaching by providing (1) cues about arm orientation at landing and/or (2) information about endpoint location or speed of the movement. (1) We will investigate how different combinations of tactile and muscle spindle feedback are integrated to localize the fingertip in space. Subjects will report location of their fingertip under different combinations of deep proprioceptive cues (with or without biceps vibration), tactile cues (with or without contact of a stationary surface), and awareness about tactile stimulus properties (naive of, aware of capability of surface motion). (2) We will determine if changes from the expected pattern of landing force during repetitive reaching will influence kinematics or reaching endpoint of subsequent reaches. We will quantify kinematics, endpoint location, and the magnitude and direction of contact forces of reaches with and without perturbations of endpoint contact. These studies will be followed up in individuals with PD, who purportedly have deficits in sensorirnotor integration, yet exhibit good anticipatory control in tactile-driven precision grip tasks. This will shed light on issues concerning sensorimotor integration of tactile input in individuals with PD, and point toward intervention strategies.